In recent years, an RFID (Radio Frequency Identification) system attracts attention and is widespread in the distribution sector, for example. The RFID system includes an RF tag (also referred to as an RFID tag), which includes an IC chip and an antenna and is attached to a product, and an RF tag reader and writer (hereinafter, simply referred to as a reader and writer), which reads information stored in the memory of the RF tag IC chip in a non-contact manner and writes information into the memory of the RF tag IC chip in a non-contact manner.
As processing in the RFID system, for example, there is processing of reading the information collectively from a plurality of RF tags during inventory work in a store or the like (hereinafter, referred to as batch read). In this case, the reader and writer emits radio waves over a distant range of several meters and executes communication with unspecified RF tags attached to a plurality of products in order to read the information stored in the RF tags collectively. In general, the RF tags to be read are disposed in a spatially wider range than the read range of an antenna of the reader and writer. Accordingly, during inventory work or the like, the tag information is acquired from RF tags while moving the antenna of the reader and writer to change the communication range.
In a known reader and writer, however, omission of reading occurred frequently because communication was generally performed while moving an antenna of the reader and writer. For this reason, a technique for detecting omission of reading and acquiring information from a tag which was not read is proposed. However, since reading work is performed while moving, the user is frequently beyond the range where communication with an unread tag is possible.